#include<iostream>
#include<vector>
#include<string>
#include<algorithm>
using namespace std;

class Solution {
public:
    int uniquePaths(int m, int n) {
        vector<vector<int>> dp(m,vector<int>(n,1));
        for(int i = 1;i<m;++i){
            for(int j = 1;j<n;++j){
                dp[i][j] = dp[i-1][j]+dp[i][j-1];
            }
        }
        return dp[m-1][n-1];
    }
};